JOURNAL OF RANGELAND SCIENCE
Year:2013 | Volume:3 | Issue:3|Papers Count:7

Vetiver grass (Vetiveria zizanioides) is known to be survived under the diverse soil and water conditions. In order to study the effects of salinity stress on the seedling growth of the desired species, a completely randomized design was conducted with 3 replications. Seeds were sown in the salty-soil plots in the greenhouse. Salinity levels were specified as 4 control ones including 20, 30 and 40 dS/m. Results showed that the seedling growth and yield were progressively declined by the increase of NaCl concentration levels.The concentrations of both chlorophylls a and b were dramatically increased by increasing NaCl and the highest and lowest values have been obtained for the levels of 40 and 4 dS/m, respectively. There were no significant differences for the leaf area and water content with the salinity of 20 dS/m as compared to the control treatment. The concentrations of chlorophylls a and b were 0.73 and 0.41 (mg/g FW) and 0.35 and 0.11 (mg/g FW) in the 40 and 4 dS/m salinity treatments, respectively. Leaf water content for 4 and 20 dS/m salinity levels has been calculated as 11.3 and 9.8 percent. But there was a significant reduction in the leaf water content with 30 and 40 dS/m salinity levels. Leaf water content with 30 and 40 dS/m salinity level was 6.3 and 5.2 %. Leaf area in 4, 20, 30 and 40 dS/m salinity levels has been computed as 172, 168.7, 81.7 and 65.2 cm2, respectively. Compared to the control treatments, there was a significant reduction in leaf area with 30 and 40 dS/m salinity levels. Our results suggest that in an EC between 4 to 20 dS/m, Vetiveria zizanioides could grow.

Soil organic matter has positive consequence for the quality and productivity of soil and also environment, agricultural and biological sustainability and conservation of biodiversity and soil. Organic matter plays an important role in the physical and chemical processes of soil and thus, it is of a great effect on the spectral characteristics of soil. This study was done in order to develop the mapping surface of soil Organic Carbon (OC) of various land uses, particularly rangelands using remote sensing technology in Dehaghan in the south of Isfahan. The data of IRS-P6 and AWIFS satellites with 49 ground control points and accuracy less than 0.3 pixels were recorded. Stratified random sampling method was used. Soil samples were collected from the depth of 0-15 cm at each point. Bulk density of soil samples was determined according to Hunk method and OC% was computed by Walky-Black method. For the preparation of land use map and False Color Composite (FCC), the supervised classification was conducted using maximum likelihood algorithm and Optimized Index Factor (OIF). In order to map the surface soil OC, the multivariate regression model was fitted using band 2 (red band) as the dependent variable.Red band had a relationship with surface soil OC in the study area. Relationship of the red band and surface soil OC content was negative. IRS-P6 and AWIFS satellite images according to the cover of spectral and spatial resolution were considered as a useful method for the preparation of land use map and the map of surface soil OC levels in the study area.

In arid and semi-arid ecosystems, shrubs may act as fertility islands but their effect may vary depending on their morphology and ecological impacts. This research was aimed to study effect of three shrubsScariola orientalis, Astragalus heratensis, and Rosa persicaon soil properties and on the microclimate conditions (temperature, luminance, and soil moisture) of their understory in the steppe rangelands of Kakhek Gonabad, Iran. Along 50-m transects, flexible plot sizes were selected to measure the microclimate factors of understory species and the open spaces next to the shrubs based on the canopy diameters of each intercepted shrubs. Soil samples were taken from understory of shrubs. The microclimatic factors of understory and open spaces were compared using paired-t test.The soil properties were analyzed under 3 shrubs and open spaces and then comparison were made usingDuncan‟s test. The results showed that temperature and luminance intensity were significantly lower in understory than the open spaces (p<0.05). Soil depth moistures (15-55 cm) were higher in understory than the open space while soil surface moistures (0-10 cm) did not vary. Among the investigated shrubs, Astragalus heratensis had the greatest facilitation effect on microclimatic factors. The soil criteria of EC (0.32 mS/cm), organic matter (1.6%), and nitrogen (0.08%) were significantly higher in understory ofAstragalus heratensis than in the open space (0.15 mS/cm, 0.39%, and 0.028%), respectively. These effects can be related to the wider canopy cover, greater stature, and possibly nitrogen fixation for Astragalus heratensis.

Poa genus has a high value for grazing and forage conservation concerning the livestock. In order to study the impacts of cold temperature and Growing Degree Days (GDD) on seedling morphological trait and phonological development of two species involvingPoa pratensis and Poa trivialis, this research was conducted in laboratory and greenhouse and outdoor of Research Institute of Forest and Rangeland in Tehran, Iran. The seed samples were moist chilled at 4oC for two weeks as compared to the control treatment.Samples of both treatments (chilling and control) were transferred into a germinator at 20±4oC for 15 days. All the pots were placed in a normal glasshouse at 20±10oC for one month. The 30th day age pots have been transferred into the cold rooms at 4oC for two weeks in comparison with control treatment. The seedling vegetative traits were measured same as the laboratory. For outdoor experiment, half of pots of greenhouse were transferred outdoor until their flowering and growth stages and GDD were recorded. In the flowering stage, morphological characteristics including stem number, stem length, peduncle length, panicle length, plants‟ fresh and dry weight of each ecotype were recorded. The collected data of each experiment were separately analyzed using factorial experiment based on completely randomized design. The results of laboratory experiment showed the significant effects of chilling (4oC) treatment on germination percent, speed of germination in both species and vigor index forP. pratensis. Regarding P. pratensis in vegetative stage, the mean values of all of traits were higher in control treatment than those of cold treatment. Similarly, in outdoor experiment, the mean values of reproductive traits in the control treatment were higher than those for cold treatment concerning both species.P. pratensishad higher mean values for all of reproductive traits as compared to P. trivialis.Results also showed that GDD of plants which were subjected to cold treatment were lower than those for control treatment for both vegetative and flowering stages. It has been concluded that cold treatment reduced flowering dates in reproductive stage.

Secale montanum is one of the important perennial grasses growing naturally in arid to semiarid pastures and rangelands, with a typical Mediterranean climate, in northern and western Iran at altitudes of 800-2900 m. In this paper, seed storage protein profiles of nine wild populations ofS. montanum from different regions of Iran and their phenotypically superior progenies as well as a multi-origin polycross (PLC) were studied. High levels of polymorphism were observed over all populations with the average number of bands and average heterozygosity. Superior progeny of different populations showed less genetic variability than wild parents in terms of band diversity, whereas PLC samples showed extremely high values of genetic parameters. Two locally common bands were observed in almost all wild parent populations, which are missing in superior progeny of different populations and PLC. These results provide highly support for the hypothesis that neutral genetic diversity has been reduced or inadvertently lost via artificial selection. Among wild parent populations and their superior progenies significant differences were observed in expected heterozygosity suggesting that more intensive breeding practices may have resulted in a further erosion of genetic variability. Neighbor-joining cluster analysis showed that wild populations and the phenotypically superior progeny of different populations were separated into two groups. This suggests that founder effects and subsequent selection have had more effect on the genetic differentiation between these accessions than geographical separation. This technology, seed storage protein profiling, has great potential for use in breeding programmes.

The objectives of this study were to understand the rainfall characteristics of the wind-water erosion crisscross region on the northern Loess Plateau, China, to provide basis for the studies on mitigation of soil erosion, estimation on surface water resources and local hydrological circle, etc. The Liudaogou Catchment with representative climatic and hydrologic conditions of wind-water erosion crisscross region at the northern Loess Plateau was chosen as the study area. Analysis of the rain intensity, duration and amount was performed for the period from May to October for five years (2006-2010). The maximum and average rain intensity of time intervals of 3 min, 5 min, 10 min, 30 min and 1 h were quantized. Rain intensity distribution of different time intervals (3 min, 5 min, 10 min, 30 min, 1h and 6 h) has been clarified to a certain degree. Rainfall events whose rainfall duration equal or less than 30 min accounted for approximately 50% of the total number of rainfall events. Rainfall event whose rainfall amount ≤ 1 mm accounted approximately 50% of annual mean rainfall events whereas their total rainfall only accounted for less than 7% of mean annual precipitation during 2006-2010. This study veritably described the main rainfall characteristics of wind-water erosion crisscross region on the northern Loess Plateau to a certain extent.

Rangelands are one of the most vulnerable parts concerning the climate changes‟ impacts. These impacts are even stronger in the arid and semi-arid areas where rangeland ecosystems are in critical conditions. Therefore, it is crucial to figure out the actual dynamics of climate variations on the rangelands. The aim of this research was to determine climate changes in Khabr rangeland, Kerman, Iran. So, four meteorological data sets of HadCM3 model including minimum and maximum temperature, precipitation and radiation rates were used to assess climate changes in the region. In this regard, climate changes during 2011-2039 were assessed by downscaling HadCM3 data using LARS-WG model under three scenarios of B1, A2 and A1B. The results have showed that the rainfall rates of spring and summer would have declining trends under all three scenarios.Minimum and maximum temperature rates would increase in all seasons, and just radiation one showed a decreasing trend for winter. Based on A1B scenario, minimum and maximum temperature rates had the highest increasing trend. Radiation and precipitation had the highest increasing and declining trends in the A2 scenario, respectively. Moreover, the increase in maximum and minimum temperature rates was averagely greater than the past and consequently despite the increasing trend in minimum and maximum temperature rates, the increase in the mean temperature rate during this period would be expected.According to the results, Khabr rangeland’s climatic conditions will be significantly different in the next 30 years and long-term and strategic planning is necessary in consistent with the management policies with these conditions.